Monday, 7 November 2005 - 9:45 AM
86-4

Regional Assessment of Risks to Soil Health - an Australian Example.

Richard MacEwan, Joanne McNeill, and Troy D. Clarkson. Department of Primary Industries, Box 3100, Bendigo Delivery Centre, Bendigo, VIC 3554, Australia

Spatial data and expert knowledge have been used in a risk assessment framework to prioritise actions within a soil health strategy for a Regional Catchment Management Authority in Victoria, Australia. A land use impact model (LUIM) was used to determine areas in the region that were potentially at risk from specific soil degrading processes. LUIM has an aspatial component that incorporates knowledge of relationships between land and soil qualities and activities on the land. It also has a spatial application that uses a GIS to map where these relationships exist or are likely to exist. A paddock scale land use layer and 1:100 000 scale soil landforms were used as the baseline data to map likelihood of soil degradation under current land use. Workshops with regional experts were used to create tables of relationships between land use practices and degradation processes, and between soil landform attributes and susceptibility to degradation processes. A Bayesian approach was used to assess uncertainty in some of the data. Explanation of terms used: Risk is a product of the likelihood that something will happen and the consequence suffered if it happens. In this study, risks to soil assets were evaluated in relation to hazards or threatening processes that degrade soils. The likelihood that soil will be degraded depends on its susceptibility to the particular threatening process and the role that land use practice may play in causing, aggravating or moderating that process (management). Hence likelihood is a product of the soil's inherent susceptibility to degradation and the imposed land use and associated practices. The consequence of degradation of a soil in response to a particular threatening process depends on how incapacitated or dysfunctional the soil becomes should that particular form of degradation occur (sensitivity) and on the productive and ecological qualities of the soil (value).

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